The invention relates to a method for creating a magnetically permeable film on a surface by deposition of a magnetic material, during which deposition a magnetic field is present near said surface, which field has a field direction which is substantially parallel to the surface.
Such a method is known from JP-A 61-16174. In the known method use is made of a coil for generating a magnetic field parallel to a surface of a substrate disposed in a sputtering device. The generated magnetic field has a fixed magnetic axis. The known method aims at forming a homogeneous magnetic thin film on the substrate.
To meet requirements imposed on present-day magnetic recording and/or reproducing devices and magnetic sensing devices, much research and development have been directed to soft magnetic thin film materials uniting a number of desired physical properties which are crucial for the performance of the devices. Examples of desired material properties are a high magnetic permeability, which may be highly anisotropic or isotropic depending on the specific device requirements, a high saturation magnetization, an as low as possible magnetostriction constant, a high resistance against corrosion and wear, a low electrical conductivity at high operating frequencies, a sizeable anisotropic magnetoresistance effect or, alternatively, a large giant magnetoresistance or spin-tunnel effect in the case of multilayer devices. For the very important class of devices which are designed to detect a small magnetic field or a small change of magnetic field high-films having a high magnetic permeability are essential and indispensable.
Several different approaches have been employed to produce films with a material of a high magnetic permeability. The resulting situation that these approaches have in common appears to be one in which the magneto-crystalline anisotropy plays a negligible role for the magnetic response, the magnetostriction constant is close to zero with the purpose to prevent that magnetostrictive anistropy contributions become active, and a uniaxial magnetic anisotropy can be induced by a magnetic field either during or after manufacturing.
The magnitude of the uniaxial magnetic anisotropy is determined largely by the material composition and process steps, such as an annealing treatment. The choice of the material composition and/or the annealing treatment is not free, but is rather restricted because of other material property requirements, as mentioned above, and because of limited crystallization in the case of amorphous materials or a limited growth of existing crystals in the case of nano-crystalline-Fe.